The Sonic Role of a Preamplifier

[trponhunter]

[QUOTE=Jerome .
But the change of the preamp and phono preamp makes a huge difference in sound.
With various preamps, the tone, the image, the weight of the notes, the frequency response, EVERYTHING in the sound changes a lot. .[/QUOTE]

Large changes in sound quality between pre amps show the degree to which they are colored - they all can't be "correct, neutral and transparent " if they sound so different.

[trponhunter]

By the way, I'm not trying to be critical, if you find the "color" you like in a pre amp, or need the additional switching and phono stage, then that's ok - it's "system matching". Personally, I prefer no pre amp with a digital system and the maximum transparency to the source I can find. If as turntable is used then a pre amp is required.

[Jerome W]

Originally Posted by trponhunter

By the way, I'm not trying to be critical, if you find the "color" you like in a pre amp, or need the additional switching and phono stage, then that's ok - it's "system matching". Personally, I prefer no pre amp with a digital system and the maximum transparency to the source I can find. If as turntable is used then a pre amp is required.

"No preamp with a digital system" :
There is a preamp in your cd player or dac with variable outputs. As soon as you have a gain attenuator : it is a preamp.
The idea of an "uncolored, correct and transparent" unit in hifi, is just a myth. It does not exist. When I say that the CJ GAT or an other component does not sound "colored" to me or sounds very neutral, it is just the impression it gives. Because all the recordings sound extremely different in tone and grain. But this is ultimately just an impression. Everything is colored.
All components have their own color, from source to speakers.

[jdandy]

Something else to consider, a preamplifier acts to attenuate, not amplify, many of its source inputs. Yes, it amplifies the moving magnet and moving coil signals, but for the most part it attenuates the line level inputs until at such point you have raised the volume level to unity gain or above. The voltage of fixed line level analog outputs for CD players, DAC's, music servers, tape players, and tuners would immediately drive most amplifiers to full rated output or beyond. These source signals must be attenuated from their fixed outputs levels for two purposes, volume control and protecting amplifiers from being driven to full rated output with no control.

Certainly there are many other aspects to the function of a well designed preamplifier, things like impedance matching, RIAA equalization for phono stages, source switching, input level matching, remote capabilities, and other functions such as EQ on certain preamplifiers. None the less, attenuation of fixed line level inputs is a large portion of the work a preamplifier handles as part of its design function.

[Cohibaman]

Originally Posted by jdandy

Something else to consider, a preamplifier acts to attenuate, not amplify, many of its source inputs. Yes, it amplifies the moving magnet and moving coil signals, but for the most part it attenuates the line level inputs until at such point you have raised the volume level to unity gain or above. The voltage of fixed line level analog outputs for CD players, DAC's, music servers, tape players, and tuners would immediately drive most amplifiers to full rated output or beyond. These source signals must be attenuated from their fixed outputs levels for two purposes, volume control and protecting amplifiers from being driven to full rated output with no control.



Certainly there are many other aspects to the function of a well designed preamplifier, things like impedance matching, RIAA equalization for phono stages, source switching, input level matching, remote capabilities, and other functions such as EQ on certain preamplifiers. None the less, attenuation of fixed line level inputs is a large portion of the work a preamplifier handles as part of its design function.

Good post!

[trponhunter]

Totally uncolored and transparent is a myth of sorts - however, it is all about degrees. There is no doubt that some components are simply better than others. With a strict protocol of the type of listening and evaluation being done, these differences can be identified and certain components will clearly be more neutral and transparent than others. Pre amps in particular are the easiest components to apply this methodology to, as they can be by passed to allow you to hear their contribution or change to the sound.

I think one of the biggest problems people run into with this type of argument is that they want to use less than only the very best recordings to take the determination. Generally, I do not use any recordings that are not live when making these types of decision, as I want to hear resolution, and the ability to capture the recordings original space and volume. Any recording that has been multi miked and put through a good bit of processing makes this type of listening more difficult. Also, many times people factor into it their personal preferences in terms of a sound they like. To me, these are slightly different things. Of course you need to be happy with your system and like the way it sounds. But confusing that with the absolute most literally "true to the source" sound is sometimes different. When doing the comparisons on proper recordings, I have yet to listen with someone else at the same time that did not come to the same conclusions and prefer the more "neutral and transparent" system.

[PHC1]

Never liked variable volume in the "digital domain" as by its inherent nature it works by chopping bits off. Why anyone would intentionally want to do that remains a puzzle to me. Not that I have not tried it, plenty of times.. Always came back to an active preamp.

[Jerome W]

Originally Posted by jdandy

Something else to consider, a preamplifier acts to attenuate, not amplify, many of its source inputs. Yes, it amplifies the moving magnet and moving coil signals, but for the most part it attenuates the line level inputs until at such point you have raised the volume level to unity gain or above. The voltage of fixed line level analog outputs for CD players, DAC's, music servers, tape players, and tuners would immediately drive most amplifiers to full rated output or beyond. These source signals must be attenuated from their fixed outputs levels for two purposes, volume control and protecting amplifiers from being driven to full rated output with no control.



Certainly there are many other aspects to the function of a well designed preamplifier, things like impedance matching, RIAA equalization for phono stages, source switching, input level matching, remote capabilities, and other functions such as EQ on certain preamplifiers. None the less, attenuation of fixed line level inputs is a large portion of the work a preamplifier handles as part of its design function.

Absolutely Dan. That's why I mentioned "gain attenuator". Except for the phono stage as you said which is both an amp and an eq.

[trponhunter]

Originally Posted by PHC1

Never liked variable volume in the "digital domain" as by its inherent nature it works by chopping bits off. Why anyone would intentionally want to do that remains a puzzle to me. Not that I have not tried it, plenty of times.. Always came back to an active preamp.

It is true that at lower levels, there can be resolution loss with a digital gain stage. However - digital gain stages are not all created equal - like analog pre amps. Also, this assumes that the analog pre amp does not also have significant faults. In my experiences, in most instances, the analog pre amps losses are significantly greater than the digital gain stage.

For some one that listens at very low levels consistently, the analog pre amp may in fact be better. However, all of this stuff is very system and sensitivity dependent.

[PHC1]

Originally Posted by trponhunter

It is true that at lower levels, there can be resolution loss with a digital gain stage. However - digital gain stages are not all created equal - like analog pre amps. Also, this assumes that the analog pre amp does not also have significant faults. In my experiences, in most instances, the analog pre amps losses are significantly greater than the digital gain stage.

For some one that listens at very low levels consistently, the analog pre amp may in fact be better. However, all of this stuff is very system and sensitivity dependent.

And if you have a high gain and/or high input sensitivity amplifier and very sensitive speakers which forces you to turn the digital domain volume down further? What's left of all the high resolution which we pay dearly for with our systems to begin with?